Archive for the ‘Bones’ Category

Prehistoric Calcium Intakes

Sunday, April 1st, 2012

Question I received:

[I]t has always bugged me that the fact that humans need to consume other animal’s milk to meet their calcium requirements seems to be evolutionarily illogical or odd. As you said vegans and people who do not eat diary have a lower calcium intake and are in the deficiency range, yet this somehow doesn’t make sense to me from a philosophical point of view….I wonder, have there been studies on vegan children and their calcium requirements? Are they lower than their non-vegan counter-parts?

On average, vegans have lower calcium intakes, with studies showing average intakes well below the RDA of 1,000 mg. But a vegan diet can have a much higher calcium intake if the person eats large amounts of greens every day. It’s just that most vegans do not eat this many greens (at least 3 servings per day of collards, kale, broccoli, mustard greens, turnip greens, or bok choy). And, of course, a vegan eating fortified foods would have higher calcium intakes.

Prehistoric human diets may have contained much larger amounts of calcium than what the average vegan gets without consuming dairy. I spent a few minutes looking around for this information today and the most recent source I could find was a paper by Eaton & Nelson from 1991. They conclude that “Stone Agers” consumed 1500 mg/day of calcium or more without dairy (1). It is a free download so if you are real interested you can take a look at the various foods that provided calcium.

To further complicate this question, sodium can cause significant loss of calcium from bones and there is evidence that our prehistoric ancestors did not consume anywhere close to as much sodium as the average person does today, which could result in a higher RDA than otherwise necessary.

All that said, there are a tremendous number of differences between modern and prehistoric lifestyles, and our ability to study prehistoric diets is rather limited, so I do not put much importance on using diets of our ancestors in order to shed much light on how we need to eat today for optimal health. And just because they might have had calcium intakes of 1500 mg, doesn’t mean that was the ideal amount even for them.

Unfortunately, there have not been any studies on the bone health of vegan children, though, anecdotally, I’m not aware of any vegan children with bone problems.

References

1. Eaton SB, Nelson DA. Calcium in evolutionary perspective. Am J Clin Nutr. 1991
Jul;54(1 Suppl):281S-287S. | link

Bone Fractures in Vegan Nuns

Wednesday, September 14th, 2011

VeganHealth.org update to Bones, Vitamin D, and Calcium:

In 2011, a follow-up (1) of an earlier study on vegan Buddhist nuns (2) was released. After two years, the vertebrae of 88 vegans and 93 omnivores were examined using x-rays. Ten women (five vegans and five omnivores) had sustained a new vertebral fracture after two years; there was no significant difference between the two groups.

Rates of bone mineral density (BMD) change were examined at the lumbar spine and femoral neck with a variety of associations found. Lumbar BMD increased with age, lean body mass, and vegetable fat; and decreased with vegetable protein and steroid use. The authors suggested that the increase in BMD of the lumbar spine was possibly due to osteoarthritis and, therefore, not a healthy phenomena.

As for the femoral neck, BMD increased with both lean and fat body mass; and decreased with age, animal fat, and ratio of animal protein to vegetable protein. This would indicate that animal protein had a negative impact on bone. To make this even a bit more complicated, the food questionnaires used by the researchers indicated that the vegans were only eating an average of 1,093 calories, 36 g of protein, and 360 mg of calcium per day. The estimated energy requirement for women their age and size is about 1,600 calories which indicates that the food intake of the vegans was possibly underestimated by one-third. The non-vegan nuns had intakes of 1,429 calories, 62 g of protein, and 590 mg of calcium per day which seems more likely.

In summary, compared to non-vegetarian Buddhist nuns, vegan nuns had a similar rate of vertebral fractures, but it is not clear how accurate were the associations with changes in BMD.

Commentary not added to VeganHealth.org:

Ten fractures in 181 women in two years seemed high to me, so I did a bit of searching and found a study (3) that indicated that in Hong Kong and Japan, the rate of vertebral fracture in women over 65 is 594/100,000 person-years. I calculate the person-year fracture rate in this Buddhist nun study to be 2,762/100,000. That’s obviously quite a bit higher, but it should be noted that the fractures in the Buddhist nun study were determined by giving an x-ray to each subject, rather than reporting a bone break, and would likely find more fractures than the study determining the 594/100,000 rate.

1. Ho-Pham LT, Vu BQ, Lai TQ, Nguyen ND, Nguyen TV. Vegetarianism, bone loss, fracture and vitamin D: a longitudinal study in Asian vegans and non-vegans. Eur J Clin Nutr. 2011 Aug 3. [Epub ahead of print] Link

2. Ho-Pham LT, Nguyen PL, Le TT, Doan TA, Tran NT, Le TA, Nguyen TV. Veganism, bone mineral density, and body composition: a study in Buddhist nuns. Osteoporos Int. 2009 Apr 7. [Epub ahead of print] Link

3. Bow CH, Cheung E, Cheung CL, Xiao SM, Loong C, Soong C, Tan KC, Luckey MM, Cauley JA, Fujiwara S, Kung AW. Ethnic difference of clinical vertebral fracture risk. Osteoporos Int. 2011 Apr 2. [Epub ahead of print] (Abstract) Link

Acid Not Linked to Calcium Loss

Friday, September 2nd, 2011

I’ve been reviewing the scientific literature on protein and bone health. As many readers know, there has been a theory that animal protein, by way of increased sulfur amino acids, causes calcium excretion leading to osteoporosis. This theory was always on shaky ground and more recent evidence has contradicted the theory. I just read a meta-analysis on the subject and added the following to the article, Bones, Vitamin D, and Calcium, on VeganHealth.org:

“Another 2009 meta-analysis found that among five well-designed studies measuring calcium balance, net acid excretion was not associated with either decreased calcium balance or a marker of bone deterioration (48).”

The paper had an interesting list of cohort studies in the discussion:

“First, during 8 yr of follow-up, fracture risk was not reduced among a cohort of 36,217 postmenopausal women who consumed either lower protein or lower NAE [net acid excretion] diets (37). Second, wrist fracture risk was highest among 1865 peri- and postmenopausal women who consumed the lowest protein intakes over 25 yr of follow-up (38). As well, a recent 2-yr trial in 276 postmenopausal women either supplemented with potassium citrate (expected to neutralize the acid of the Western diet) or encouraged to consume increased fruit and vegetables showed that these interventions did not reduce bone turnover or decrease bone loss (36).”

The take home message, which I’ve written about before, is that not eating animal protein does not protect you from osteoporosis. Make sure you get enough calcium, vitamin D, and even (plant) protein.

References

36. Macdonald HM, Black AJ, Aucott L, Duthie G, Duthie S, Sandison R, Hardcastle AC, Lanham New SA, Fraser WD, Reid DM. Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial. Am J Clin Nutr. 2008 Aug;88(2):465-74. (Link) Free article available.

37. Dargent-Molina P, Sabia S, Touvier M, Kesse E, Bréart G, Clavel Chapelon F, Boutron-Ruault MC. Proteins, dietary acid load, and calcium and risk of postmenopausal fractures in the E3N French women prospective study. J Bone Miner Res. 2008 Dec;23(12):1915-22. (Link) Free article available.

38. Thorpe DL, Knutsen SF, Beeson WL, Rajaram S, Fraser GE. Effects of meat consumption and vegetarian diet on risk of wrist fracture over 25 years in a cohort of peri- and postmenopausal women. Public Health Nutr. 2008 Jun;11(6):564-72. Epub 2007 Aug 9. (Link) Free article available.

48. Fenton TR, Lyon AW, Eliasziw M, Tough SC, Hanley DA. Meta-analysis of the effect of the acid-ash hypothesis of osteoporosis on calcium balance. J Bone Miner Res. 2009 Nov;24(11):1835-40. (Link)

Vitamin D Update

Wednesday, June 22nd, 2011

In November of 2010, the Institute of Medicine released a report, Dietary Reference Intakes for Calcium and Vitamin D. This was a long-awaited report given that in the time since their previous report from 1997, many researchers have been arguing that:

  • In addition to causing rickets and osteomalacia, vitamin D deficiency can lead to many other diseases including cancer and autoimmune diseases.
  • Optimal amounts of vitamin D in the blood are between 80 to 100 nmol/l (32 to 40 ng/ml), which was much higher than previously thought.
  • Many more people than ever before are deficient in vitamin D, especially given the higher levels thought to be optimal.

I also promoted the higher levels for vitamin D, especially given that studies published in the late 2000s on vitamin D listed categories of “insufficiency” and “deficiency” that were in line with the more recent, higher recommendations by some researchers.

But when the Institute of Medicine released their report last November, they did not agree, for the most part, with the three points above. Their Report Brief summarizes their findings (on both calcium and vitamin D):

The committee assessed more than one thousand studies and reports and listened to testimony from scientists and stakeholders before making its conclusions. It reviewed a range of health outcomes, including but not limited to cancer, cardiovascular disease and hypertension, diabetes and metabolic syndrome, falls, immune response, neuropsychological functioning, physical performance, preeclampsia, and reproductive outcomes. This thorough review found that information about the health benefits beyond bone health—benefits often reported in the media— were from studies that provided often mixed and inconclusive results and could not be considered reliable. However, a strong body of evidence from rigorous testing substantiates the importance of vitamin D and calcium in promoting bone growth and maintenance.

The IOM did increase the RDA for vitamin D from 400 IU to 600 IU for adults. But they continue to recommend ideal levels of vitamin D to be between 40 – 50 nmol/l (16 – 20 ng/ml).

I recently finished going back through many of the study summaries on the Bones, Vitamin D, and Calcium page of VeganHealth.org and adjusted them to reflect the IOM’s findings. I also added some information from other vitamin D studies, such as one on tanning beds, another on vitamin D2 vs. D3, and a 2011 report from EPIC-Oxford on vitamin D levels in vegetarians.

The good news is that many vegans who were struggling to raise their vitamin D levels to 80 nmol/l no longer need to worry about that, as 40 – 50 nmol/l is apparently fine and is the recommendation I will be promoting unless the IOM changes its recommendations in the future or there is other overwhelming evidence to do so.

This does not negate the importance of vegans making sure they get a reliable source of vitamin D. As I’ve pointed out many times, I have been contacted by many vegans whose vitamin D levels dropped well below 40 nmol/l and developed symptoms of deficiency. And even without overt symptoms (such as fatigue, or muscle or bone pain), you should not allow your bones to be harmed because you are neglecting vitamin D. My recommendations have stayed pretty much the same – if you are not getting enough sun to produce plenty of vitamin D, you should take about 1,000 IU of vitamin D per day.

What Should I Be Tested For?

Tuesday, November 30th, 2010

I am regularly asked by vegans what they should be tested for. Here is a run down:

Vitamin B12

As I say in Should I Get My B12 Status Tested?

Vegans do not need to get their homocysteine or B12 levels checked merely because they are vegan. Rather, being vegan means that you should get a regular, reliable source of vitamin B12 from fortified foods and/or supplements. (Though if you’ve gone a month or so without a reliable source of B12, you should replenish your stores as described in Step 1 of the Recommendations.)

About 2% of people do not absorb B12 well. While this has nothing to do with being vegan, it is nice to know if you are such a person. You will not be able to tell unless you first have a reliable source of B12 for at least a few weeks before your B12 level is checked. Additionally, there are specific tests that directly measure B12 absorption.

If you get your B12 level checked, please note that eating seaweeds can falsely inflate B12 levels. Methods for determining B12 levels do not distinguish between B12 and some inactive B12 analogues. Many seaweeds contain a variety of inactive B12 analogues. Someone who is eating large amounts of seaweed may have serum B12 levels well above normal, but much of it could be inactive B12 analogues.

Vitamin D

This is probably the one nutrient that vegans really can benefit from getting tested even if they do not have any symptoms of poor health.

Calcium

The body keeps blood calcium levels relatively constant regardless of your diet, so getting calcium levels tested doesn’t tell you much of anything (other than that you are not seriously ill). Getting your bone mineral density tested is the best way to find out what shape your bones are in. I don’t necessarily recommend this, unless you have reason to believe you might have osteoporosis. I’ve said it many times before, but I’ll say it again – most vegans should drink calcium-fortified non-dairy milks (or other foods) or take a calcium supplement.

Omega-3s

If you’re taking a DHA supplement, then you don’t need to be tested unless you suspect you’re having a cognition or other possible omega-3-related problem. Here are some testing companies.

There is a more common test that could shed some light on your EPA status—blood clotting time. Most doctors test for this routinely. If your blood is clotting too fast, you might be lacking EPA. I rarely hear from a vegan whose blood is clotting too fast.

Iron

If a doctor is going to draw blood, getting an iron panel to see if you have enough (or too much) iron is a good idea, especially for menstruating women.

Iodine

There is no direct test for iodine. Like B12, it’s best to just make sure you’re getting enough (but not too much). Iodine deficiency (and excess) can lead to thyroid problems, so getting your thyroid tested would be an indirect indicator. Click here for more on iodine.

And that covers it for any routine nutrients to test for regarding the vegan diet.

Vitamin D to Prevent Flu in School Children

Tuesday, November 2nd, 2010

Matt (thanks!) sent me the article Flu Season Secret Weapon: Vitamin D To The Rescue. I got a copy of the original paper (1) and here is the deal:

Children in Japan, average age of about 8 to 12, were given 1,200 IU of vitamin D3 or placebo for 4 months and the cases of flu and other symptoms were measured. Children getting vitamin D had 42% less cases of influenza A (.58, .34 – .99). The effect of vitamin D was stronger among kids who had started school later, indicating the ones who started school earlier had built up better immunity.

A reduction in influenza A was not seen in kids who had asthma, although asthma attacks were reduced in those receiving vitamin D by a whopping 83% (.17, 0.04 – .73).

Cases of influenza B did not differ between the two groups, possibly due to different defense mechanisms for preventing influenza A versus B.

Reference

1. Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr. 2010 May;91(5):1255-60. Epub 2010 Mar 10. Link.

Calcium Supplements: Are They Safe?

Monday, October 11th, 2010

In July, a meta-analysis of the effect of calcium supplementation on heart attacks was published in the British Medical Journal (1). They found that people taking calcium supplements were more likely to have a heart attack. People have asked me if I think this means vegans should not supplement with calcium.

If you look at the study (the full paper is available for free at the link in the abstract below), they found that the increased risk of heart attack was limited to people who started out with a dietary calcium intake of 700 mg/day or more. Most vegans do not get that much calcium through foods. In most of the studies they examined, the level of calcium supplementation was substantially higher than 500 mg.

This study indicates that if you are an adult who gets 700 mg of calcium from your diet (including fortified foods), you probably shouldn’t take more than about a 300 mg supplement of calcium per day.

The DRI for calcium for ages 9 to 18 is 1,300 mg. This meta-analysis was conducted on older people trying to prevent osteoporosis and is probably not applicable for teenagers, whose bones are still building.

The DRI for calcium for people over 50 is 1,200. My recommendation for people in this age group who want to meet the DRI is to get at least 700 mg per day through foods and only supplement enough to make up the difference.

It’s worth noting that some observational studies of calcium intake (from foods, not supplements) have shown higher intakes to be protective against heart disease.

1. Bolland MJ, Avenell A, Baron JA, Grey A, MacLennan GS, Gamble GD, Reid IR.
Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010 Jul 29;341:c3691.

D2 v. D3

Thursday, September 16th, 2010

I have added some more study summaries to the section on vitamin D2 vs. D3 in the article Bones, Vitamin D, and Calcium on the VeganHealth.org site. My conclusion has remained the same – in amounts of around 1,000 to 2,000 IU per day, vitamin D2 is as effective as vitamin D3.

Here are the new paragraphs:

Glendenning et al. (39) (2009) compared 1,000 IU of D2 vs. D3 in people with vitamin D insufficiency who had hip fractures. After three months, those who supplemented with D3 had a 31% or 52% (depending on how they were measured) greater increase in 25(OH)D levels than those supplementing with D2. However, parathyroid hormone levels did not differ between groups, leading the researchers to question whether the difference in 25(OH)D levels were of biological importance.

Gordon et al. (40) (2008), treated 40 infants and toddlers with vitamin D deficiency. Each were assigned to one of three 6-week regimens: 2,000 IU oral vitamin D2 daily, 50,000 IU vitamin D2 weekly, or 2,000 IU vitamin D3 daily. At the end of the trial, participants’ 25(OH)D levels went from an average of 42.5 to 90 nmol/l (17 to 36 ng/ml), and there were no significant differences between treatment groups.

Thatcher et al. (41) (2009) gave children with rickets one oral dose of 50,000 IU of vitamin D2 or D3. After three days, 25(OH)D levels rose from approximately 50 to 72 nmol/l (20 to 29 ng/ml) for both groups. Calcitriol levels also increased similarly in both groups (by about 70%), however, calcium absorption did not increase, leading the researchers to conclude the rickets were not caused by low vitamin D deficiency. This should not be a surprise since the baseline average level of 50 nmol/l (20 ng/ml) of 25(OH)D should be adequate to prevent rickets.

References at Bones, Vitamin D, and Calcium.

Vitamin D2 Update

Wednesday, June 16th, 2010

The vitamin D section of VeganHealth.org has been updated with this new information:

In June 2010, a vegan who had been diagnosed with vitamin D deficiency wrote me saying that his weekly 50,000 IU of Vitamin D2, prescribed by his doctor for 12 weeks, succeeded in raising his vitamin D levels from 13 ng/ml on Jan 27 to 72 ng/ml on May 4. For long-term maintenance, his doctor recommended 1200 IU per day.

Calcium Supplement Absorption

Tuesday, May 25th, 2010

Dear Jack,

I read a post from a woman being treated for osteoporosis. She said a good test for a calcium supplement is to put it in a glass of white vinegar (same pH as a stomach) for 20 min to see if it dissolves. Is this really a good test for a calcium supplement?

I tried it and hardly any of my calcium tablet dissolved in that time. If this does matter can you recommend a vegan calcium supplement that will break down either tablet, powder or liquid?

Answer:

For some background, according to Advanced Nutrition & Human Metabolism (1999), the pH of the stomach is about 2.0. According to Krause’s Food, Nutrition, & Diet Therapy (2000), it ranges from 1 to 4. Vinegar tends to be about 2.0 to 3.0.

The New York State Department of Health has a web page Commonly Asked Questions About Calcium Supplements:

“Calcium must dissolve in your stomach before it can be absorbed in your intestines and then used by your body. A USP symbol on the label of a calcium supplement means that is it will dissolve in your stomach. If your supplement does not have a USP symbol, you can easily test it to find out if it will dissolve. Simply put the supplement into a glass of clear vinegar. This creates an acidic environment much like that of your stomach. Stir the solution occasionally. If the calcium supplement disintegrates within 30 minutes, it should dissolve in your stomach, too. If the supplement does not completely dissolve, choose an alternative calcium supplement.

“If you are taking acid blockers for indigestion, reflux or other gastrointestinal conditions, your body may use calcium citrate better than other calcium compounds. Acid blockers reduce the acid in your gastrointestinal tract that is usually required for calcium absorption. However, unlike other calcium compounds, calcium citrate does not require an acid environment for calcium absorption.”

I did a test with my Trader Joe’s Calcium Magnesium & Zinc supplement, which uses calcium carbonate – I broke one tablet in half and put it in 1/5 cup of apple cider vinegar. After 8 minutes it was completely dissolved.

The Office of Dietary Supplements at the National Institutes of Health has the following to say on their Dietary Supplement Fact Sheet: Calcium:

“The two main forms of calcium in supplements are carbonate and citrate. Calcium carbonate is more commonly available and is both inexpensive and convenient. Both the carbonate and citrate forms are similarly well absorbed, but individuals with reduced levels of stomach acid can absorb calcium citrate more easily. Other calcium forms in supplements or fortified foods include gluconate, lactate, and phosphate. Calcium citrate malate is a well-absorbed form of calcium found in some fortified juices [8]. The body absorbs calcium carbonate most efficiently when the supplement is consumed with food, whereas the body can absorb calcium citrate equally effectively when the supplement is taken with or without food [9].”